Contact lenses that you can wear while you sleep—this earth- shattering concept arouses no less interest and excitement than the Pill did when it was first introduced. This is the glamour lens that everybody wants to know about and have, and is probably the lens of the future. Like the Pill, which forever altered our sexual standards, the extended-wear contact lens promises to usher in a new era and change our attitudes toward visual correction. But the similarity doesn’t end there: Though this lens seems to be the answer to every contact lens wearer’s prayers, it has not yet been perfected. It is definitely not for everyone, and some practitioners are reluctant to prescribe it at all.
Canada, Australia, and Europe enjoyed several types of extended-wear contact lenses several years before we did. However, there is no Food and Drug Administration in those parts of the world, and because of this lack of strict monitoring control and quality, these lenses have posed a health problem, especially as related to corneal complications. Read the rest of this entry »
These lenses offer a unique blend of the advantages of both hard and soft lenses. They provide excellent visual acuity, and correct most types of astigmatism better than soft lenses (but not quite as well as conventional hard lenses). The gas-permeable lenses correct astigmatism in the same manner as the hard lenses by forming a perfectly round, smooth inner surface filled with tears. Multifocal gas-permeable lenses are also available for the presbyope. They are almost as durable as hard lenses, and much more so than soft lenses. You can expect gas-permeable lenses to last up to five years. Since the lenses are firm in consistency, they are handled easily and with greater confidence than are soft lenses. They can be accurately reproduced, so there are none of the surprises that can occur when reordering a soft lens. Read the rest of this entry »
For a long time, tinted soft lenses were not available in this country because of lack of FDA approval. Because the lenses are large and extend beyond the iris onto the white part of the eye, a complete dark tint would also look rather odd. But the transparency of a nontinted lens makes it difficult to see, especially when dropped. The advertising campaign based on the soft lens’s near-perfect resemblance to a drop of water is no exaggeration. No tint also means no glare reduction, but since photosensitivity in soft-lens wearers is relatively rare, this is a minor disadvantage.
However, this ban may no longer be an issue for soft-lens wearers, because in June of 1981 a tinting process for soft lenses was made available. The physician may send any FDA approved soft contact lens to a special laboratory in North Carolina in order to be tinted according to certain specifications. Read the rest of this entry »
Surprisingly, all soft lenses are classified as drugs by the FDA because of their ability to combine chemically with medications placed in the eye. (Hard lenses do not.) The FDA must approve every new lens or lens modification as well as the solutions used in their care. Unlike hard lenses and their solutions, which have been around long enough to have been standardized, soft lenses have no established standards because the FDA insists that insufficient information still exists that would provide reasonable assurance of their safety and effectiveness. Every type of soft lens now on the market has been tested first on laboratory animals (which are “sacrificed” so their eyes can be removed and thoroughly examined), and then on a minimum of four hundred human “guinea pigs” for six months (whose eyes—thank goodness—are examined in situ). Read the rest of this entry »
Make sure that the lens is centered properly on the cornea before attempting to remove it. Once more you have a choice of methods; your specialist will help you decide which is best for you. Always place your left hand beneath the right eye when removing the right lens and vice versa, and tuck your chin close to your chest so your face is parallel to your work surface. In all the conventional methods the mechanism is the same: The edges of the lids are forced behind the edges of the lens, to “pry” it off. Always begin by opening the eyelids very widely, as if you were surprised, so the eyelid edges clear the diameter of the lens. (The following methods are for the right eye; reverse directions for the left eye.) Read the rest of this entry »
Hard contacts can be made more comfortable by drilling tiny holes or fenestrations through them, allowing more tears to reach the cornea. The holes are usually 0.3 mm in diameter. (Anything less than that and they become plugged with mucus; anything larger and vision is adversely affected.) They are best placed close to the center of the lens, since that is the area of the cornea that is most likely to be oxygen deprived. Because a contact lens naturally rotates on the eye, the area directly under the fenestration changes constantly, and sometimes only one hole is needed. But usually three holes are necessary. Read the rest of this entry »
Contact Lenses Care .
